Re: [Discuss-gnuradio] GRC Polyphase Channelizer examples?

[John Ackermann N8UR]

Tom Rondeau said the following on 10/14/2011 12:01 PM:

> John,
> You've almost got it right except for the taps. The "taps" parameter is
> the FIR taps of the prototype filter, which then gets partitioned among
> the N channels of the channelizer.
>
> While there is no example in GRC readily available, you can look at the
> channelize.py example in:  gnuradio-examples/python/pfb/
>
> Specifically, line 49 is where the filter taps are created. Notice that
> the sample rate is the sample rate at the input to the channelizer while
> the bandwidth and transition width are defined for the channel
> bandwidths. This makes a fairly long filter that is then split up
> between the N channels of the PFB.

Thanks, Tom.  So it appears that you use a firdes.lowpass type function 
in the taps setting.  I've done that and I now get somewhat more sane 
results on the output FFT.

However, I'm still seeing massive underruns when I assume the same 
sample rate as the input.  Is there a decimation going on (i.e., 
output_rate = input_rate/num_channels or something like that)?

John